#include<iostream>
#include <unistd.h>
#include<cerrno> // errno.h
#include<cstring> // string.h
#include<sys/wait.h>
#include<sys/types.h>

//fork之后子进程是能拿到父进程的数据的 --- 通信吗？写时拷贝，对方都看不到
//char buffer[1024];//不行的

const int size = 1024;

std::string getOtherMessage()
{
    static int cnt = 0;
    std::string messageid = std::to_string(cnt);
    cnt++;
    pid_t self_id = getpid();
    std::string stringpid = std::to_string(self_id);
    std::string message = "messageid:";
    message += messageid;
    message += "my pid is:";
    message += stringpid;

    return message;
}

//子进程进行写入
void SubProcessWrite(int wfd)
{
    int pipesize = 0;
    std::string message = "father,I am you son process!";
    char c = 'A';
    while(true)
    {
        std::cout << "++++++++++++++++++++++++++++++++++++++++++++++++" << std::endl;
        std::string info = message + getOtherMessage();//这条消息就是子进程发给父进程的消息
        write(wfd, info.c_str(), info.size());//写入管道的时候，没有写入\0,有没有必要？没有必要！
        std::cerr << info << std::endl;

        sleep(1);//子进程慢点写
        // write(wfd, &c, 1);
        // std::cout << "pipesize:" << ++pipesize << "write charator is:" << c++ << std::endl;
        // if(c == 'G') break;

        // sleep(1);
    }
}

//父进程进行读取
void FatherProcessRead(int rfd)
{
    char inbuffer[size]; //c99后支持
    while(true)
    {
        sleep(2);
        std::cout << "--------------------------------------------" << std::endl;
        ssize_t n = read(rfd, inbuffer, sizeof(inbuffer) - 1);
        if(n > 0)
        {
            inbuffer[n] = 0;//这个位置给为'\0'
            std::cout << inbuffer << std::endl;
        }
        else if(n == 0)
        {
            //如果read的返回值是0，表示写端直接关闭了，我们读到了文件的结尾
            std::cout << "client quit,father get return val:" << n << "father quit too!" << std::endl;
            break;
        }
        else
        {
            std::cerr << "read error" << std::endl;
            break;
        }
        //sleep(1);
        //break;   
    }
}
int main()
{
    //1.创建管道
    int pipefd[2];
    int n = pipe(pipefd);//输出型参数， rfd wfd
    if(n != 0)
    {
        std::cerr << "errno:" << errno << " : " << "errstring: " << strerror(errno) << std::endl;
        return 1;
    }
    //pipefd[0] -> 0 -> r(嘴巴读)  pipefd[1] -> 1 -> w(笔写)
    std::cout << "pipefd[0]: " << pipefd[0] << ", pipefd[1]: " << pipefd[1] << std::endl;
    sleep(1);

    //2.创建子进程
    pid_t id = fork();
    if(id == 0)
    {
        std::cout << "子进程关闭不需要的fd了，准备发消息了" << std::endl;
        // 子进程 -- write
        // 3.关闭不需要的fd
        close(pipefd[0]);
        //if(fork() > 0) exit(0);
        SubProcessWrite(pipefd[1]);


        close(pipefd[1]);
        exit(0);
    }

    std::cout << "父进程关闭不需要的fd了，准备收消息了" << std::endl;
    sleep(1);
    //父进程 --- read
    //3.关闭不需要的fd
    close(pipefd[1]);

    FatherProcessRead(pipefd[0]);
    //std::cout << "5s,father close rfd" << std::endl;
    //sleep(5);
    close(pipefd[0]);
    int status = 0;
    pid_t rid = waitpid(id, &status, 0);
    if(rid > 0)
    {
        std::cout << "wait child process done,exit sig:" << (status&0x7f) << std::endl;
        std::cout << "wait child process done,exit code(ign):" << ((status >> 8)&0xff) << std::endl;
    }
    return 0;
}